fstab(5) — Linux manual page


FSTAB(5)                      File formats                      FSTAB(5)

NAME         top

       fstab - static information about the filesystems

SYNOPSIS         top


DESCRIPTION         top

       The file fstab contains descriptive information about the
       filesystems the system can mount. fstab is only read by programs,
       and not written; it is the duty of the system administrator to
       properly create and maintain this file. The order of records in
       fstab is important because fsck(8), mount(8), and umount(8)
       sequentially iterate through fstab doing their thing.

       The file is not read by mount(8) only but often is used by many
       other tools and daemons, and proper functionality may require
       additional steps. For example, on systemd-based systems, it’s
       recommended to use 'systemctl daemon-reload' after fstab

       Each filesystem is described on a separate line. Fields on each
       line are separated by tabs or spaces. Lines starting with '#' are
       comments. Blank lines are ignored.

       The following is a typical example of an fstab entry:

           LABEL=t-home2   /home      ext4    defaults,auto_da_alloc      0  2

   The first field (fs_spec).
       This field describes the block special device, remote filesystem
       or filesystem image for loop device to be mounted or swap file or
       swap device to be enabled.

       For ordinary mounts, it will hold (a link to) a block special
       device node (as created by mknod(2)) for the device to be
       mounted, like /dev/cdrom or /dev/sdb7. For NFS mounts, this field
       is <host>:<dir>, e.g., knuth.aeb.nl:/. For filesystems with no
       storage, any string can be used, and will show up in df(1)
       output, for example. Typical usage is proc for procfs; mem, none,
       or tmpfs for tmpfs. Other special filesystems, like udev and
       sysfs, are typically not listed in fstab.

       LABEL=<label> or UUID=<uuid> may be given instead of a device
       name. This is the recommended method, as device names are often a
       coincidence of hardware detection order, and can change when
       other disks are added or removed. For example, 'LABEL=Boot' or
       'UUID=3e6be9de-8139-11d1-9106-a43f08d823a6'. (Use a
       filesystem-specific tool like e2label(8), xfs_admin(8), or
       fatlabel(8) to set LABELs on filesystems).

       It’s also possible to use PARTUUID= and PARTLABEL=. These
       partitions identifiers are supported for example for GUID
       Partition Table (GPT).

       See mount(8), blkid(8) or lsblk(8) for more details about device

       Note that mount(8) uses UUIDs as strings. The string
       representation of the UUID should be based on lower case
       characters. But when specifying the volume ID of FAT or NTFS file
       systems upper case characters are used (e.g UUID="A40D-85E7" or

   The second field (fs_file).
       This field describes the mount point (target) for the filesystem.
       For swap area, this field should be specified as `none'. If the
       name of the mount point contains spaces or tabs these can be
       escaped as `\040' and '\011' respectively.

   The third field (fs_vfstype).
       This field describes the type of the filesystem. Linux supports
       many filesystem types: ext4, xfs, btrfs, f2fs, vfat, ntfs,
       hfsplus, tmpfs, sysfs, proc, iso9660, udf, squashfs, nfs, cifs,
       and many more. For more details, see mount(8).

       An entry swap denotes a file or partition to be used for
       swapping, cf. swapon(8). An entry none is useful for bind or move

       More than one type may be specified in a comma-separated list.

       mount(8) and umount(8) support filesystem subtypes. The subtype
       is defined by '.subtype' suffix. For example 'fuse.sshfs'. It’s
       recommended to use subtype notation rather than add any prefix to
       the first fstab field (for example 'sshfs#example.com' is

   The fourth field (fs_mntops).
       This field describes the mount options associated with the

       It is formatted as a comma-separated list of options and is
       optional for mount(8) or swapon(8). The usual convention is to
       use at least "defaults" keyword there.

       It usually contains the type of mount (ro or rw, the default is
       rw), plus any additional options appropriate to the filesystem
       type (including performance-tuning options). For details, see
       mount(8) or swapon(8).

       Basic filesystem-independent options are:

           use default options. The default depends on the kernel and
           the filesystem. mount(8) does not have any hardcoded set of
           default options. The kernel default is usually rw, suid, dev,
           exec, auto, nouser, and async.

           do not mount when mount -a is given (e.g., at boot time)

           allow a user to mount

           allow device owner to mount

           or x-<name> for use by fstab-maintaining programs

           do not report errors for this device if it does not exist.

   The fifth field (fs_freq).
       This field is used by dump(8) to determine which filesystems need
       to be dumped. Defaults to zero (don’t dump) if not present.

   The sixth field (fs_passno).
       This field is used by fsck(8) to determine the order in which
       filesystem checks are done at boot time. The root filesystem
       should be specified with a fs_passno of 1. Other filesystems
       should have a fs_passno of 2. Filesystems within a drive will be
       checked sequentially, but filesystems on different drives will be
       checked at the same time to utilize parallelism available in the
       hardware. Defaults to zero (don’t check the filesystem) if not

FILES         top

       /etc/fstab, <fstab.h>

NOTES         top

       The proper way to read records from fstab is to use the routines
       getmntent(3) or libmount.

       The keyword ignore as a filesystem type (3rd field) is no longer
       supported by the pure libmount based mount utility (since
       util-linux v2.22).

HISTORY         top

       The ancestor of this fstab file format appeared in 4.0BSD.

SEE ALSO         top

       getmntent(3), fs(5), findmnt(8), mount(8), swapon(8)

REPORTING BUGS         top

       For bug reports, use the issue tracker at

AVAILABILITY         top

       fstab is part of the util-linux package which can be downloaded
       from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>. This page
       is part of the util-linux (a random collection of Linux
       utilities) project. Information about the project can be found at
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have
       a bug report for this manual page, send it to
       util-linux@vger.kernel.org. This page was obtained from the
       project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2023-12-22. (At that time, the date of the most recent commit
       that was found in the repository was 2023-12-14.) If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page,
       or you have corrections or improvements to the information in
       this COLOPHON (which is not part of the original manual page),
       send a mail to man-pages@man7.org

util-linux 2.39.594-1e0ad      2023-07-19                       FSTAB(5)

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